Supercritical fuel-air mixing at the injector exit for diesel conditions

This research seeks to develop and validate accurate, physics-based, numerical submodels and framework, which can be implemented in CFD software to enable it to accurately predict high-pressure diesel spray. The combined experimental-computational effort consists of (1) acquiring spatially and temporally resolved scalar measurements of fuel-oxidizer mixing in the near field of the jet for a range of supercritical or nearly supercritical test conditions relevant to diesel engines, (2) developing real-fluid model and code to calculate thermo-physical properties of diesel surrogates and their mixtures with oxidizer of interest at a wide range of operating conditions, especially at pressures near and above the critical conditions.

Time-resolved measurements of the unsteady flow field in a rotating detonation engine (RDE)

This research seeks to characterize the flow at the discharge of a Rotating Detonation Engine (RDE) using time-resolve particle image velocimetry (PIV), OH chemiluminescence, and/or OH PLIF techniques at approximately 20 kHz.  The RDE will be operated with methane fuel and oxygen-enriched air to replicate conditions relevant to power generating gas turbines. Flow measurements will be acquired between rotating shocks and at radial locations corresponding to inner and outer walls of RDE combustor.  We are interested in time-resolved measurements of flow velocities, selected combustion species, dynamic pressure and temperature. The test rig shall provide a back pressure to the RDE combustor up to the safe operating limits of the facility.

Combustion diagnostics to co-optimize Advanced Compression Ignition (ACI) engines

The goal of this project is to accelerate deployment of co-optimized fuels and engines that will reduce fuel consumption, and criterion pollutants and greenhouse gas (GHG) emissions. Specifically, we will acquire combustion measurements in a constant pressure flow rig with optical access, and develop models to predict combustion characteristics based on known fuel and ambient conditions. We are targeting prediction of properties relevant to lean lifted flame combustion (LLFC), a mixing-controlled low temperature combustion (LTC) strategy to reduce soot production in Advanced Compression Ignition (ACI) engines. 

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Our research group has conducted several studies to demonstrate the favorable spray and low-emission combustion characteristics of FB atomizer using conventional fuels and alternative fuels including biodiesel, straight VOs, waste byproducts, and glycerol. ​of FB atomization. Liquid fuel is supplied through the central fuel tube, and atomizing air is supplied through the outer tube surrounding the fuel tube. Upstream of the exit orifice is a small gap between the orifice inlet and fuel tube exit that allows the atomizing air to mix with the liquid fuel before exiting through the orifice. In FB atomization, the gap designated by H must be less 0.25 D, where D is the fuel tube inside diameter. H/D  ≤ 0.25 results in radial flow of the atomizing air across the gap H, and a stagnation region is formed in the gap. Thus, the atomizing air is bifurcated with a portion of the air flowing into the fuel-tube and the rest being directed towards the exit-orifice of the FB injector. While most of the atomizing air exits through the orifice, a small portion penetrating upstream forms bubbles and mixes turbulently with the incoming fuel. The two-phase mixture with small air bubbles, then leaves the orifice forming a fine spray. The rapid bursting of air bubbles as they experience sudden pressure drop across the orifice is the mechanism for FB primary atomization that results in a spray with fine droplets even for high-viscosity liquids.